The titanium silicalite (sometimes called as Ti—Si) molecular sieve is a new heteroatom-containing molecular sieve developed in 1980s. The TS-1 with MFI structure, TS-2 with MEL structure, MCM-22 with MWW structure, and TS-48 having larger pores have been synthesized.
In the currently known direct hydrothermal synthesis of the Ti—Si molecular sieve, the organic silicon source and/or the inorganic silicon source are generally used.
The organic silicon source such as the organic silicate TEOS is costly, and the molecular sieve made therefrom has a lower content of effective component. It is difficult to increase the solid content in the crystallization product in the synthesis of the molecular sieve. In addition, in the production of the molecular sieve, a large amount of ethanol is evaporated. It is difficult to collect and reuse the evaporated ethanol. In order to reduce the cost, the inorganic silicon source is used to partly or completely substitute the organic silicon source. However, the Ti—Si molecular sieve made from the inorganic silicon source has a lower activity. In addition, the Ti—Si molecular sieve obtained by using the organic quaternary ammonium salt as the template agent has a lower activity. Furthermore, the Ti—Si molecular sieve obtained by the known method has a higher micropore volume and a lower mesopore volume.
Prior Art 1: U.S. Pat. No. 4,410,501
Prior Art 2: CN 1260241A